chore: proxy image preview in frontend (#11957)

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **New Features**
	- Images and icons in bookmark cards are now loaded through an image proxy for improved reliability and consistency.
	- Embed blocks for GitHub, Loom, and YouTube now display banner and creator images via an image proxy service for enhanced image loading.

- **Refactor**
	- Simplified backend URL handling and proxy logic for images, resulting in more efficient processing and reduced complexity.
	- Consolidated image proxy middleware and services into a shared adapter module for streamlined imports and improved maintainability.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/__tests__/__snapshots__/worker.e2e.ts.md

@@ -67,10 +67,10 @@ Generated by [AVA](https://avajs.dev).
     {
       description: 'Test Description',
       favicons: [
-        'http://localhost:3010/api/worker/image-proxy?url=https%3A%2F%2Fexample.com%2Ffavicon.ico',
+        'http://example.com/favicon.ico',
       ],
       images: [
-        'http://localhost:3010/api/worker/image-proxy?url=https%3A%2F%2Fexample.com%2Fimage.png',
+        'http://example.com/image.png',
       ],
       title: 'Test Title',
       url: 'http://example.com/page',
@@ -82,7 +82,7 @@ Generated by [AVA](https://avajs.dev).
     {
       charset: 'gbk',
       favicons: [
-        'http://localhost:3010/api/worker/image-proxy?url=https%3A%2F%2Fexample.com%2Ffavicon.ico',
+        'http://example.com/favicon.ico',
       ],
       images: [],
       title: '你好，世界。',
@@ -95,7 +95,7 @@ Generated by [AVA](https://avajs.dev).
     {
       charset: 'shift_jis',
       favicons: [
-        'http://localhost:3010/api/worker/image-proxy?url=https%3A%2F%2Fexample.com%2Ffavicon.ico',
+        'http://example.com/favicon.ico',
       ],
       images: [],
       title: 'こんにちは、世界。',
@@ -108,7 +108,7 @@ Generated by [AVA](https://avajs.dev).
     {
       charset: 'big5',
       favicons: [
-        'http://localhost:3010/api/worker/image-proxy?url=https%3A%2F%2Fexample.com%2Ffavicon.ico',
+        'http://example.com/favicon.ico',
       ],
       images: [],
       title: '你好，世界。',
@@ -121,7 +121,7 @@ Generated by [AVA](https://avajs.dev).
     {
       charset: 'euc-kr',
       favicons: [
-        'http://localhost:3010/api/worker/image-proxy?url=https%3A%2F%2Fexample.com%2Ffavicon.ico',
+        'http://example.com/favicon.ico',
       ],
       images: [],
       title: '안녕하세요, 세계.',